Process for protecting and coloring concrete



Patented Dec. 29, 1942 PROCESS FOR PROTECTING AND COLOR- ING CONCRETEEdward W. Scripture, Jr., Shaker Heights, Ohio No Drawing. ApplicationDecember 12, 1938, Serial No. 245,212

9 Claims,

This invention relates to the coloring of structures of concrete, mortarand artificial stone and has particular reference to floors, walks,roadways and the like from Portland or other hydraulic cement. Theobjects of the invention are the provision of simple and inexpensivemeans for imparting a uniform durable color to a hardened concretestructure of uncolored or natural cement colored concrete or mortar.

It is well known that to produce a colored concrete surface color shouldbe introduced integrally in the concrete mix at the time the concrete isplaced either in the form of a suitable pigment or of a coloredaggregate or both.

Nevertheless the situation frequently arises that the coloring of theconcrete has been neglected at the time of layingor placing for onereason or another, and it is desired to color the plain concretesubsequently. Hitherto no satisfactory solution to this problem has beenoffered.

There have been two methods of coloring plain concrete which have hadfairly general application. These are painting and chemical staining.

Painting has never proved entirely satisfactory due chiefly to twocauses, In contact with concrete in the presenceof even small amounts'of moisture, painting is unsuccessful either because the paint itselfis deteriorated by thealkali oi.

the cement or because the film blisters or peels;

Paint, furthermore, even if not attacked by moisture and alkali in theconcrete, is not resistant to abrasion so that only short life can beexpected under wear and frequent renewals are required. Chemicalstaining, usually with iron or copper salts, has been fairlysatisfactory except for certain limitations. The available colors arelimited to brown and green and intermediate shades derived from mixturesof these two. The

concrete to be stained must be in excellent con'- dition for successfulapplication,"the results proa duced are entirely unpredictable, and itis impossible to secure an even or uniform color.

The coating and finishing of walls, blocks,

,bricks, floors, or other structures composed of,

.or smaller degree. Taking cement, concrete, or

lime mortar for example, the lime present (as well as other alkaliesusually occurring together with the lime) attacks resin acids and fattyacids, as well as their glycerides (such as the linolein of linseed oil)forming lime soaps. On the one hand, this destroys the bond of thecalcareous materials by the removal of lime, or the destruction ofbonding compounds containing it,

and on the other, the formation of the lime soaps the idea of forminglime soaps, but this also affects the bond of the surface while the limesoaps do not prove in this case desirable components of the coating astheytend to oxidize and become friable and are hydrolytic. i

In any 'form' of concrete Ci -.ting containing acid material for thepurpose of neutralizing the alkalinity ofconcrete, as is the case withcertain.

types of concrete primers the speed of neutralization has to beconsidered. If the acid component acts rapidly, neutralization may beeffected before the coating has set and dried. If the action of the acidcomponent is slow, neutralization and reaction may go on after settingand drying of the composition, thus causing rupturing of the coating andits ultimate destruction. The resin acids differ from the fatty acidsinthis respect. They are slower than the fatty acids in neutralizingactivity, so slow in fact that under ordinary conditions a coatingcompound has opportunity to dry and harden before neutralizing reactionsare fairly under way, and these reactions subsequently progress to thedetriment of the coating.

The following brief comparisons may serve to explain the differencesnoted. The fats as glycerides form well characterized bodies. The resinsare largely bodies resulting from condensation, are very fluctuating incomposition and the nature of their compounds is not at all wellestablished at the present time. The copals which are so extensivelyused in varnish making vary in composition very greatly. Manila copal,for

example, may have an acid number of 135,and a saponiflcation value of185 while Angola copal will perhaps give an acid number of 60 and asaponification value of I35. Borneo copal will give an acid number ofabout 145 and a saponiflcation value of, say, 180. Amber contains about30% resin acids and nearly 70% of saponifiable esters. Common rosin hasan acid number of about 140 although this varies considerably withdifferent grades. However, the uncertain composition of resins makes allthese figures of indifferent value.

It will be apparent that neither the vegetable oils composed of fattyacid glycerides nor the natural resins containing as they doconsiderable proportions of saponifiable material are suitable for thepurposes of my invention. Some attempts have been made to overcome thisdifficulty with natural resins by removing from the resin thesaponifiable matter before incorporating it in the coating composition.Particularly this has been the case with resins separated from jelutongof different qualities known in the trade, according to the source fromwhich they are derived, as palembang, pontianak, sarawak, and the like.Pontianak resin especially has been separated and treated for use as acoating material but the pontianak resin in and of itself, whether freeof saponifiable matter or in its original condition, is not a very goodcoating material, being more or less friable and brittle.

The foregoing difficulties encountered in the use of drying oils andnatural resins in coating compositions for cement surfaces may beovercome by the use of synthetic resins which form tough, impermeableand transparent films and which are themselves unsaponifiable andsubstantially immune to attack by alkali. Amon such resins are thoseformed by the treatment of rubber with hydrogen chloride, metalchlorides,

' or halogens, particularly chlorine, and known in the trade, forexample, as Tornesit and Pliolite. Carleton Ellis in his book entitledThe Chemistry of Synthetic Resins, volume II, published in 1935 by theReinhold Publishing Co. of New cosity than those of the originalmaterial. They do not burn. Somewhat similar compounds are formed by theaction of the hydrogen halides on rubber and related materials.Othersynthetic resins, such as the co-polymers of vinyl chloride andvinyl acetate, known as Vinylite, have similar properties and aresuitable for the purpose of my invention. It is suflicient that thesynthetic resin employed be chemically inert and unsaponifiable, that itbe soluble ina suitable solvent to form a solution of low viscosity, andthat it form a tough and relatively impermeable film.

Numerous methods of finishing concrete surfaces have been proposed.Painting has been used but as has been pointed out, paint on an alkalinesurface is unsatisfactory. Many attempts have been made to overcome thedifliculties due to the action; of alkali on paint. These have taken theform of treatments of the surface to neutralize the alkali or ofapplying a priming coat before the application of the paint. While theuse of such materials as zinc sulphate, magnesium fluosilicate, orsimilar materials, to neutralize the alkali, have been to some extentbeneficial the remedy is incomplete since York, on page 1117, footnote83, states that chlorinated rubber'hasrbeen placed on the market underthe tradekfame Tornesit.

On page 1102 of the above book, Ellis states that when 10% by weight ofchlorostannic acid is milled into ,rubber and heated for two to fivehours at 130 C. to 150 C., a tough balata-like material results. Longheating or excessive temperature forms a hard ebony-like substance. Infootnote 132, Ellis states that these resins have been placed on themarket by The Goodyear Tire & Rubber Company as molding materials andalkali-resistant coatings under the trade name Pliolite.

The reaction products of rubber and chlorostannic acid are described inBruson Patent No. 1,797,188; this patent states that these reactionproducts contain combined chlorine.

The phrase chlorine-containing rubber derivative as used herein includesproducts as obtained by the treatment of rubber withchlorin'e-containing reagents, such as chloro stannic acid or chlorine,which are used in the preparation of Pliolite and Tornesit,respectively. The halogens react directly with rubber, guttapercha, orbalata to form an interesting series of compounds possessing propertiesintermediate between those of rubber and the brittle natural resins.Highly chlorinated rubber, together with derivatives containing lesschlorine, furnish a graduated series of products with elastic propertiesvarying from that. of the original rubber to one of a tough leatherlikeresin. The halogenated bodies are chemically inactive and are moresoluble than the original stock in various solvents. The solutionspossess much lower visonly the alkali on the surface is neutralized andsubsequently alkali from the interior will penetrate to the surface.Priming coats such as treated oils, particularly Chinawood oil, variouscompositions of natural resins including the resins derived fromjelutong, particularly pontianak resin, have been .more or lesssuccessful but usually fail in,one or more respects. Either the primeritself is not completely immune to attack by alkali, or it does notcompletely protect the overlying paint from attack, or the bond of theprimer to the concrete surface is poor, or the bond between the primerand the paint is poor. In order to improve the bond, roughening of thesurface has been employed, and this is of some benefit, but where theroughening is solely for the purpose of providing a bond for a surfacefilm it is only a partial solution of the problem. Regardless of themethods used to prepare or treat the surface preparatory to painting.where the final finish is a paint coat it is always subject to wear. andgives only temporary resistance to abrasion.

In.addition to the use of chemical stains, that is solutions ofcompounds, usually of copper or iron, which react with the cement toform colored reaction products, it has been proposed to use dyes insolution in various organic solvents. While it is possible in this wayto color a cement surface the dyes being transparent or translucentrather than opaque do not give complete hiding of the surface and do notproduce a uniform, strong color. Furthermore, most dyes are more or lesssusceptible to fading in the light and the permanence of colors soproduced is questionable.

It is an object of this invention to impart a pleasing uniform color touncolored surfaces which will be resistant to moisture and alkali fromthe concrete and to abrasion from traflic or other wear, to provide afinish which will be resistant to most corrosives which are apt to comein contact with the surface, to provide a finish which is easilymaintained and renewed if necessary and to secure these results by meansof a reasonably simple and inexpensive treatment rocess.

In order to secure a colored finish which is durable and which will notbe pushed from the surface by the action of moisture, alkali, or saltsolutions in the concrete it is necessary thatsuitable colored pigmentor pigments should be carried into the pores of the concrete and shouldbe held there by a binding medium which is resistant to attack bymoisture and alkali. It is further desirable that an alkali and moistureresistant substance should penetrate into the concrete and remain thereto minimize the penetration of moisture to the surface. The colortreatment should not, however, be such that a heavy coat, as of paint,should remain on the surface but rather the color should penetrate intothe pores with only sufiicient on the surface to hide and color thesurface. Finally to secure resistance to abrasion and provide easymaintenance the surface should be finished with a wax or waxlikesubstance which can be polished to form a wearing film which ispreferably not'slippery. Thus, dependence is not placed on the pigmenttreatment for a wearing surface but only for a waterproofing treatmentwhich will hold the color pigment firmly in place in the surface.

I have found that for pigments it is desirable to use finely dividedalkali resistant pigments such as the inorganic oxides of iron,chromium,

manganese, etc., and also ultramarine blue. It is also desirable to usepigment dyestuffs such as the toluidine toners, Hansa Yellow, MonastrelBlue, etc.,. which are more brilliant in color, which are more finelydivided and therefore will more readily enter into the pores of theconcrete, and which are alkali resistant. To bind the pigments into theconcrete surface I have found that solutions of alkali-resistantsynthetic resins are quite effective. Synthetic resins of thetype ofVinylite may .be used; also synthetic rubber resins such as chlorinatedrubber, cyclicized rubber and rubber hydrochloride. are very effective.As a penetrating, waterproofing substance I employ a resinous liquidwhich is of comparatively low viscosity but non-volatile and non-dryingsuch as a chlorinated diphenyl, which is also nonsaponifiable. Owing tothe saponifying action of alkali on drying oils such as tung and linseedoils, it is undesirable to use such oils in conjunction with thiscoloring process. While it may be possible to apply each of the'threesubstances described, pigment, synthetic resin, and penetrant separatelywith good results, it is preferable to incorporate the pigment and thepenetrant in the resin solution so that all three may be applied in oneoperation. The proportion of pigment in the composition should besufficient to fill the pores of the concrete and to just hide and colorthe surface of the concrete, but insufficient to increase substantiallythe viscosity of the composition or to cause the building up of a thickfilm like that of a paint on the surface of the concrete. Thewaterproofing penetrant should be present 'in sufficient proportion togive effective waterproofing and to help in carrying the pigment intothe pores, but should not be present insuflicient quantity to impair thehardening of the synthetic resin. The resin in a suitable solvent shouldbe present in sufficient quantity to bind'the pigment mineral spiritsmay be used in making solutions of these resins, an excess of mineralspirits tends to cause the formation of a more permeable film and thisis particularly true where the mineral spirits used is of the same orlower volatility than follows:

Xylol c.c Rubber resin (Pliolite) g 10 Chlorinated diphenyl c.c 5 Oxidepigment g 4 Pigment dyestufi g 2 For the final finish coat I employ awax or waxlike substance which is resistant to attack by moisture oralkali such as a high-melting point wax as canauba, or a waxlikesubstance such as a chlorinated naphthalene (Halowax). The latter hasthe desirable quality that it produces a wearing surface which iswaxlike in that it may be-polished but is not slippery. .These waxes orwaxlike materials may be applied either as solutions, either true orcolloidal in suitable solvents, usually in the form of paste or asemulsions in water. I prefer their application as emulsions since thisavoids the danger of softening the resin which holds thepigment duringap plication of the finish. Where a wax or waxlike substance with amelting point higher than the boiling point of water is used it isnecessary to employ a small amount of a suitable solvent to lower themelting point of the wax or waxlike substance to permit thepreparationof an emulsion. To avoid the formation of streaks which are hard topolish out and to avoid the clouding of the color underneath by anywhitening of the waxlike finish, it is often desirable to incorporateinto the finish a small amount of pigment. An example of a suitablecomposition is as follows:

The process whereby the concrete surface is treated with these coloringand finishing compositions comprises preferably four steps. First, theconcrete surface is thoroughly cleaned.- Second, the surface is etchedwith a dilute solution (10%) of a suitable acid (hydrochloric) in orderto open the pores and allow penetration, the resultant salts arethoroughly washed from the surface and the surface allowed to dry. Ifthe surface is already porous the acid etching may be omitted. I'hird,to the dry open surface is applied the composition comprising pigment,penetrant, and resin solution by scrubbing in with stiff brushes andbrushing out with a soft brush to bring to an even surface. Fourth, whenthe pigmented treatment has dried the waxlike finish is brushed evenlyover the surface, allowed to dry, and polished.

It will 'be seen that I have provided a process for treating concrete orcement structures whereby a'durable, wear-resistant-finish is obtained,which adds to the appearance of the structure and also protects itssurface to a large extent from the action of the elements.

Many modification may be made of my invention without departing from thespirit thereof, and it is intended that it be limited only by the priorart and the scope of the appended claims.

What I claim is:

l. The'process of imparting a uniform, durable color to a hardenedconcrete or mortar structure, which comprises applying to the surface ofsuch structure a liquid chlorinated diphenyl of relatively lowviscosity, a coloring material, and a solution of at least one member ofthe group consisting of chlorine-containing rubber derivatives andchlorine-containing vinyl resins, and subsequently applying a coat of ahigh melting point wax-like substance.

2. The process of imparting a uniform, durable color to a hardenedconcrete or mortar structure, which comprises applying to the surface ofthe structure a solution of at least one member of the group consistingof chlorine-containing rubber derivatives and chlorine-containing vinylresins, and containing a liquid chlorinated diphenyl of relatively lowviscosity and an alkali fast coloring material, and applying a finishingcoat of a high melting point alkali resistant, waxlike substance inaqueous dispersion, said coatings being further characterized by havingno substantial amounts of drying oils.

3. The process of imparting a uniform, durable color to a hardenedconcrete or mortar structure. which comprises applying to the surface ofthe structure a solution of at least one member of the group consistingof chlorine-containing rubber derivatives and chlorine-containing vinylresins, and containing liquid chlorinated diphenyl of relatively lowviscosity and an alkali fast coloring material, and applying a finishingcoat of a high melting point alkali resistant, wax-like substance inaqueous dispersion.

4. The process of imparting a uniform, durable color to a hardenedconcrete or mortar structure, which comprises applying to the surface ofthe structure a solution of a chlorine-containing rubber derivative andcontaining a liquid chlorinated diphenyl, a pigment and an alkali fastcoloring material, and applying a finishing coat of a high melting pointalkali resistant wax-like substance in aqueous dispersion, said coatingsbeing further characterized by having no substantial amounts of dryingoils.

5. The process of imparting a uniform, durable color to a hardenedconcrete or mortar structure, which comprises applying to the surface ofthe structure a solution containing chlorinated rubher, a liquidchlorinated diphenyl of relatively low viscosity and an alkali fastcoloring material, and then applying a coat of an aqueous dispersion ofa high melting point wax-like substance.

6. The process of imparting a uniform, durable color to a hardenedconcrete or mortar structure, which comprises applying to the surface ofthe structure a solution containing a chlorine-containing vinyl resin, apenetrating non-drying, liquid chlorinated diphenyl of relatively lowviscosity, and an alkali fast coloring material, and then applying acoat of an aqueous dispersion of a high melting point wax-likesubstance.

7. The process of imparting a uniform, durable color to a hardenedconcrete or mortar structure,

which comprises applying to the surface of the structure a solutioncontaining rubber hydrochloride, a liquid chlorinated diphenyl of relatively low viscosity and an alkali fast coloring material, and thenapplying a coat of an aqueous dispersion of a high melting pointwax-like substance.

8. In a process of imparting a uniform, durable color to a hardenedconcrete or mortar structure, the steps which comprise cleaning thesurface of said structure, etching said surface with acid to increaseits porosity, applying to said surface a solution of chlorine-containingrubber derivatives, said solution containing a liquid chlorinateddiphenyl of relatively low viscosity and an alkali fast coloringmaterial, and then applying a finishing coat of an aqueous dispersion ofan alkali resistant wax-like substance.

9. The process of imparting a uniform durable color to a hardenedconcrete or mortar structure which comprises applying to the surface ofsuch a structure a liquid chlorinated diphenyl of relatively lowviscosity, a coloring material and a solution of a chlorine-containingrubber derivative and subsequently applying a coat of chlorinatednaphthalene in aqueous dispersion.

1 EDWARD W. SCRIPTURE, JR.

